You can check by inspecting the mailing headers.

The Obama campaign uses Blue State Digital to send emails. The Romney campaign uses ExactTarget.

That's pretty interesting to learn. Blue State Digital's allegiance is obvious. ExactTarget is based in Indiana, a red state.

(Though I'm sure their greatest allegiance is to green.)

At least two years ago, most campaigns were using systems built by their respective parties, which were tightly integrated with their own voter databases. Things may have changed, but having a sibling working a big senate campaign this election cycle, I can tell you there's still a lot of room for improvement.